diff --git a/clang/include/clang/Basic/CodeGenOptions.def b/clang/include/clang/Basic/CodeGenOptions.def
--- a/clang/include/clang/Basic/CodeGenOptions.def
+++ b/clang/include/clang/Basic/CodeGenOptions.def
@@ -32,6 +32,7 @@
                 llvm::DebugCompressionType::None)
 CODEGENOPT(RelaxELFRelocations, 1, 0) ///< -Wa,--mrelax-relocations
 CODEGENOPT(AsmVerbose        , 1, 0) ///< -dA, -fverbose-asm.
+CODEGENOPT(Dwarf64           , 1, 0) ///< -gdwarf64.
 CODEGENOPT(PreserveAsmComments, 1, 1) ///< -dA, -fno-preserve-as-comments.
 CODEGENOPT(AssumeSaneOperatorNew , 1, 1) ///< implicit __attribute__((malloc)) operator new
 CODEGENOPT(Autolink          , 1, 1) ///< -fno-autolink
diff --git a/clang/include/clang/Driver/Options.td b/clang/include/clang/Driver/Options.td
--- a/clang/include/clang/Driver/Options.td
+++ b/clang/include/clang/Driver/Options.td
@@ -2084,6 +2084,8 @@
   HelpText<"Generate source-level debug information with dwarf version 4">;
 def gdwarf_5 : Flag<["-"], "gdwarf-5">, Group<g_Group>,
   HelpText<"Generate source-level debug information with dwarf version 5">;
+def gdwarf64 : Flag<["-"], "gdwarf64">, Group<g_Group>, Flags<[CC1Option]>,
+  HelpText<"Generate DWARF64 debug information.">;
 
 def gcodeview : Flag<["-"], "gcodeview">,
   HelpText<"Generate CodeView debug information">,
diff --git a/clang/lib/CodeGen/BackendUtil.cpp b/clang/lib/CodeGen/BackendUtil.cpp
--- a/clang/lib/CodeGen/BackendUtil.cpp
+++ b/clang/lib/CodeGen/BackendUtil.cpp
@@ -561,6 +561,7 @@
   Options.MCOptions.MCFatalWarnings = CodeGenOpts.FatalWarnings;
   Options.MCOptions.MCNoWarn = CodeGenOpts.NoWarn;
   Options.MCOptions.AsmVerbose = CodeGenOpts.AsmVerbose;
+  Options.MCOptions.Dwarf64 = CodeGenOpts.Dwarf64;
   Options.MCOptions.PreserveAsmComments = CodeGenOpts.PreserveAsmComments;
   Options.MCOptions.ABIName = TargetOpts.ABI;
   for (const auto &Entry : HSOpts.UserEntries)
diff --git a/clang/lib/Driver/ToolChains/Clang.cpp b/clang/lib/Driver/ToolChains/Clang.cpp
--- a/clang/lib/Driver/ToolChains/Clang.cpp
+++ b/clang/lib/Driver/ToolChains/Clang.cpp
@@ -4760,6 +4760,9 @@
                     IsIntegratedAssemblerDefault))
     CmdArgs.push_back("-fno-verbose-asm");
 
+  if(Args.hasArg(options::OPT_gdwarf64))
+    CmdArgs.push_back("-gdwarf64");
+
   if (!TC.useIntegratedAs())
     CmdArgs.push_back("-no-integrated-as");
 
diff --git a/clang/lib/Frontend/CompilerInvocation.cpp b/clang/lib/Frontend/CompilerInvocation.cpp
--- a/clang/lib/Frontend/CompilerInvocation.cpp
+++ b/clang/lib/Frontend/CompilerInvocation.cpp
@@ -905,6 +905,7 @@
       Args.hasFlag(OPT_fcoverage_mapping, OPT_fno_coverage_mapping, false);
   Opts.DumpCoverageMapping = Args.hasArg(OPT_dump_coverage_mapping);
   Opts.AsmVerbose = !Args.hasArg(OPT_fno_verbose_asm);
+  Opts.Dwarf64 = Args.hasArg(OPT_gdwarf64);
   Opts.PreserveAsmComments = !Args.hasArg(OPT_fno_preserve_as_comments);
   Opts.AssumeSaneOperatorNew = !Args.hasArg(OPT_fno_assume_sane_operator_new);
   Opts.ObjCAutoRefCountExceptions = Args.hasArg(OPT_fobjc_arc_exceptions);